Pathway · 3 proteins
Arginine and proline metabolism
Proteins of this group that KEGG places on its “Arginine and proline metabolism” map for Aquifex aeolicus.
How it works
This map links arginine and proline, which are both made from glutamate. The three proteins here make proline: glutamate is phosphorylated, reduced to a semialdehyde that closes into a ring on its own, and the ring is reduced to proline.
Grouped by KEGG pathway map. The explanation above is the atlas’s own; the map itself covers more organisms than Aquifex.
Its proteins
| Protein | EC | Reaction (UniProt) | Metal or cluster | Amino acids | Certainty |
|---|---|---|---|---|---|
| Gamma-glutamyl phosphate reductase | 1.2.1.41 | L-glutamate 5-semialdehyde + phosphate + NADP(+) = L-glutamyl 5-phosphate + NADPH + H(+) | — | 435 | Step named |
| Glutamate 5-kinase | 2.7.2.11 | L-glutamate + ATP = L-glutamyl 5-phosphate + ADP | — | 356 | Step named |
| Pyrroline-5-carboxylate reductase | 1.5.1.2 | L-proline + NADP(+) = (S)-1-pyrroline-5-carboxylate + NADPH + 2 H(+) | — | 265 | Step named |
Also part of this pathway
These proteins are described under another pathway, but also take part here.
| Protein | EC | Reaction (UniProt) | Metal or cluster | Amino acids | Certainty |
|---|---|---|---|---|---|
| Probable aspartate/prephenate aminotransferaseHome: Cysteine and methionine metabolism | 2.6.1.1; 2.6.1.78 | L-aspartate + 2-oxoglutarate = oxaloacetate + L-glutamate | — | 394 | Step named |
| Ornithine decarboxylaseHome: Not yet placed in a pathway | — | — | — | 390 | Step named |
| S-adenosylmethionine decarboxylase proenzymeHome: Cysteine and methionine metabolism | 4.1.1.50 | S-adenosyl-L-methionine + H(+) = S-adenosyl 3-(methylsulfanyl)propylamine + CO2 | — | 135 | Step named |
| Polyamine aminopropyltransferase 1Home: Not yet placed in a pathway | 2.5.1.16 | S-adenosyl 3-(methylsulfanyl)propylamine + putrescine = S-methyl-5'-thioadenosine + spermidine + H(+) | — | 280 | Unspecified |
Origins
How could proline and arginine, both made from glutamate, have been supplied before cells?
One step on the way to proline needs no enzyme: glutamate semialdehyde closes into a ring by itself, and the ring is then reduced to proline.
That same spontaneous ring closure would destroy the route to arginine. The cell keeps the two routes apart by acetylating the arginine branch at its first step, so a single intermediate feeds two products without one consuming the other.
From the books: Nelson & Cox, Lehninger Principles of Biochemistry, p. 861; Horton et al., Principles of Biochemistry, p. 597.
The wider question for this part of the cell: origins for making the twenty amino acids.
Sources
- KEGG map aae00330 (enzymes of this organism highlighted)
Other pathways in this group: Aromatic amino acids · Branched-chain amino acids · Aspartate-family branches · Nitrogen assimilation · RNA maturation · Folate-linked carbon transfer · Arginine biosynthesis · Cysteine and methionine metabolism · Histidine metabolism · Lysine biosynthesis · Phenylalanine, tyrosine and tryptophan biosynthesis · Not yet placed in a pathway